The vertebral locking and retrieving system is generally composed of vertebral locking devices such as vertebral fastening nails, hooks sold under the trademark LUGUE and the like. These locking devices must be united with the vertebral locking rod in order to work effectively. A brief review of techniques relating to the fastening of the locking devices with the vertebral rod is in order. There are several conventional fastening methods, such as the nut and bolt fastening system, the lateral screw fastening system, the upper nut and bolt fastening system, the three-point shear clamp mechanism introduced by the DANEK Corporation of the United States, the V-groove connection design, sold under the trademark ISOLA and the spherical universal joint fastening system. According to the conventional technique, the locking devices, such as vertebral nails. LUGUE hooks and the like, are fastened with the vertebral locking rod by means of nuts and bolts. The nut-and-bolt method is defective in that the nut and the bolt are vulnerable to becoming loosened, and that the screwing of the nut onto the bolt is often a time-consuming task which prolongs the surgical operation. With a view to overcoming the shortcomings of the conventional technique described above, the Zimmer Corporation of the United States introduced a system, sold under the trademark MODULOCK system which employs the snap lock method. However, the MODULOCK system has an inherent drawback in that its constituent parts are provided with openings, which can be caused to become wider by the engaging force of the constituent parts of the MODULOCK system and the vertebral locking rod. In addition, the MODULOCK system is further defective in design in that its constituent parts are fastened indirectly with the vertebral locking rod by means of the intermediate snap rings. As a result, the fastening effect of the MODULOCK system is seriously undermined.